a few days ago I released this open source project T48T.
A simple 3D multiplayer online, each connected browser or new window of the browser is a new player, Threejs make the 3D render and Tile38 storage the positions and detect the collisions, both connected over websockets.
The project was very interesting for me because I can used a in-memory geolocation data store as a multiuser collisions detector.
The repos of the client and the server
I hope this can be useful for other.
Thanks for your feedback